The present invention relates to a direction detecting apparatus which detects a direction of a light source and a surveying system provided with the direction detecting apparatus.
In recent years, there has been increased cases where a corner cube is used as an object to be measured and where a surveying instrument with a tracking function tracks the corner cube and measures a position of the corner cube.
In this case, in order to accurately measure a distance between a main body of a surveying instrument and a corner cube, it is necessary′ that the corner cube is positioned vertically above a measurement point. Normally, the corner cube is provided at an upper part of a supporting pole, and an operator sets a lower end of the supporting pole at the measurement. Point and vertically supports the supporting pole. Further, a bubble tube is provided at the supporting pole so that the operator can vertically support the supporting pole and so that the operator confirms whether or not the supporting pole is vertically placed by the bubble tube.
In this case, whether or not the supporting pole is supported in a vertical state depends on a level of skill of the operator, and there is a problem that an error becomes larger in a case where a supporting pole is longer, and the like.